Domain wall dynamics of ferrimagnets influenced by spin current near the angular momentum compensation temperature

We report on a theoretical study of the spin current excited dynamics of domain walls (DWs) in ferrimagnets in the vicinity of the angular momentum compensation point. For a two-sublattice ferrimagnet effective Lagrangian and nonlinear dynamic equations are derived taking into account both the spin torques and the external magnetic field. The dynamics of the DW is calculated before and after the Walker breakdown for any direction of the spin current polarization. It is shown that for the in-plane polarization of the spin current, the DW mobility reaches a maximum near the temperature of the angular momentum compensation. On the contrary, for the out-of-plane spin polarization, the spin current with densities below the Walker breakdown does not excite DW dynamics. After overcoming the Walker breakdown, the domain wall velocity increases linearly with increasing current density. In this configuration of spin current polarization, the possibility of a gigahertz oscillation dynamics of the quasiantiferromagnetic vector under the action of a dampinglike torque at the angular momentum compensation point is demonstrated. Possible structures for experimental demonstration of the considered effects are discussed.